What controversy did Franklin Pierce have to deal with?

Franklin Pierce faced significant controversy during his presidency primarily due to the Kansas-Nebraska Act of 1854, which allowed settlers in those territories to determine whether they would allow slavery. This act repealed the Missouri Compromise and led to violent conflicts known as "Bleeding Kansas" between pro-slavery and anti-slavery settlers. Pierce's support of the act and his administration's handling of the violence alienated many in the North and contributed to the growing sectional divide in the U.S.